This invention relates to a novel method of separating helium, oxygen, nitrogen or carbon dioxide from gas mixtures containing such gases using membranes comprising perfluorinated polymers with pendant ionomeric moieties.
In recent years there has been an increasing demand for the separations of gases in gas mixtures. One such separation is the separation of oxygen from nitrogen. In certain embodiments, it is desirable to use enriched oxygen streams, for example, to enhance combustion of certain materials. In other embodiments, it is desirable to have nitrogen with very little oxygen in it, for example, in fruit or food storage and shipping. Another such separation is the separation of helium from natural gas. There is also a demand for separating carbon dioxide from gas streams containing carbon dioxide, including separating carbon dioxide from natural gas. It is also desirable to separate nitrogen from natural gas or light hydrocarbons including methane.
One such method for performing these separations is to contact the gas mixture with a membrane which is selectively permeable for one of the components of the gas mixture. In such embodiment, the selectively permeable gas passes through the membrane at a faster rate than the other gas, and by collecting the selectively permeated species on the opposite side of the membrane, some degree of separation can be achieved.
The need is to find membranes which provide a high permeability for the selectively permeable species, a high ratio of permeation of the selectively permeable species as compared to the non-selectively permeable species, and good mechanical properties.